[Dnsmasq-discuss] How are inconsistent DNS records handled

Simon Kelley simon at thekelleys.org.uk
Tue Nov 13 09:39:40 GMT 2007


Felix Engel wrote:
> Good morning list,
> 
> last night the dnsmasq instance startet putting a high load on our
> upstream server by sending out around 3000 requests/second for the same
> domain. In the logfile this looks like this:
> /========================= daemon.log
> Nov 12 16:49:24 dhcp-sss dnsmasq[7925]: query[AAAA] www.citeseer.org from
> +angelus
> 6.26.128
> Nov 12 16:49:24 dhcp-sss dnsmasq[7925]: forwarded www.citeseer.org to ns1
> Nov 12 16:49:32 dhcp-sss last message repeated 2748 times
> Nov 12 16:49:32 dhcp-sss dnsmasq[7925]: query[AAAA] www.citeseer.org from
> +angelus
> Nov 12 16:49:32 dhcp-sss dnsmasq[7925]: forwarded www.citeseer.org to ns1
> Nov 12 16:49:43 dhcp-sss last message repeated 2617 times
> \=========================== end daemon.log
> 
> A query for citeseer.org points to dns.nec-labs.com. This server however,
> points to the .org root server when queried for citeseer.org, which in turn
> points to dns.nec-labs.com.
> 
> However I do not understand, why dnsmasq keeps forwarding requests even
> though no client is sending requests anymore. Maybe someone here has
> already seen this behaviour and can shed some light?
> 

What version of dnsmasq are you using? Some releases before, I think,
2.36 had a bug where they would retry a query forever if the upstream
server return an error code of SERVFAIL. It's possible that the
inconsistency in that domain is causing exactly that, and tickling the
dnsmasq bug.

Cheers,

Simon.



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